It said the costs incurred to date are "a lot less" than the income the wind turbine and solar park could generate.

The council believes the project, on 900 acres (365 hectares) of its farmland, could generate an income of £30m net profit for wind power alone and more than £114m for solar and wind power over 20 years.

The FOI also revealed planning application fees of nearly £450,000, a feasibility study costing nearly £800,000 and legal fees of just under £30,000.

'Benefit every resident'

John Harris from the Newborough Landscape Protection Group said: "They've spent £1.5m up until the end of June and it's still increasing, yet we don't yet know if they'll get permission and if they don't it'll be a waste of money."

Leader of Peterborough City Council Marco Cereste said: "Given the scale and complexity of the proposals, the costs incurred to date are a lot less than the income that could be generated and are in line with expectations."

He added that "harnessing the power of renewable energy" will "generate income that can benefit every resident of our city".